Abstract: A method of manufacturing a hermetically-sealed chamber with an electrical feedthrough includes the step of hermetically fixing an electrode to a substrate in a predetermined location on the substrate. A passage is formed through the substrate through the predetermined location such that at least a portion of the electrode is exposed to the passage. The passage is then at least partially filled with an electrically conductive material. A housing is then formed including the substrate such that the housing defines a chamber, with the electrode being disposed within the housing and the chamber being hermetically sealed. The electrode within the chamber can be placed in electrical communication with an exterior electrical component by way of the electrically conductive material in the passage.

Abstract: A coupling loop or antenna is provided that can be used with a system that determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. In one embodiment multiple energizing loops energize an implanted sensor and a sensor coupling loop connected to an input impedance that is at least two times greater than the inductance of the sensor coupling loop receives the sensor signal.

Abstract: A disclosed method determines fluid pressure inside a vessel without compromising the integrity of the vessel. A sensor is positioned in operative communication with the external wall of the vessel such that expansion of the external wall of the vessel exerts a force against the sensor that is directed substantially radially outward with respect to the vessel. A substantially radially inward force is caused to be directed against the sensor in response to the substantially radially outward force exerted by the external vessel wall. The sensor can thus be used to detect the magnitude of the substantially radially outward force. A disclosed apparatus determines fluid pressure inside a vessel without compromising the integrity of the vessel. The apparatus includes a sensor and a band operatively associated with the sensor and configured to at least partially encircle the vessel so as to retain the sensor in operative communication against the external wall of the vessel.

Abstract: A pressure cavity is durable, stable, and biocompatible and configured in such a way that it constitutes pico to nanoliter-scale volume. The pressure cavity is hermetically sealed from the exterior environment while maintaining the ability to communicate with other devices. Micromachined, hermetically-sealed sensors are configured to receive power and return information through direct electrical contact with external electronics. The pressure cavity and sensor components disposed therein are hermetically sealed from the ambient in order to reduce drift and instability within the sensor. The sensor is designed for harsh and biological environments, e.g. intracorporeal implantation and in vivo use. Additionally, novel manufacturing methods are employed to construct the sensors.

Abstract: A method of manufacturing a sensor for in vivo applications includes the steps of providing two wafers of an electrically insulating material. A recess is formed in the first wafer, and a capacitor plate is formed in the recess of the first wafer. A second capacitor plate is formed in a corresponding region of the second wafer, and the two wafers are affixed to one another such that the first and second capacitor plates are arranged in parallel, spaced-apart relation.

Abstract: A ventricular assist device comprises a sheet of hydraulically actuated material that can be affixed to prescribed locations on the surface of the heart to assist areas of the heart that do not contract normally. The material is comprised of a network of contractible unit cells that individually contract when fluid is pumped into them. These unit cells are connected together in a network that causes the sheet to contract radially inward. This contraction causes the sheet to transmit forces to the heart to assist in its natural contraction. A sensing function coordinates the contraction of the sheet with the contraction of the heart. The change in shape of the device is accomplished by distributing pressurized fluid throughout the spaces of the device by way of a network of channels. When pressure is removed from the fluid system, it assumes a deenergized “rest” position in which it does not transmit any forces to the surface of the heart.

Abstract: A coupling loop or antenna is provided that can be used with a system that determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. A cable attached to the coupling loop provides maximum isolation between the energizing signal and the sensor signal by maximizing the distance between the coaxial cables that carry the signals and maintaining the relative positions of the coaxial cables throughout the cable assembly.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: In the disclosed method of manufacturing an implantable wireless sensor, a cavity is etched in one side of a first substrate. A conductive structure are formed on the base of the cavity. A second conductive structureare formed on a surface of a second substrate, and the two substrates are mutually imposed such that the two conductive plates and coils are disposed in opposed, spaced-apart relation. A laser is then used to cut away perimeter portions of the imposed substrates and simultaneously to heat bond the two substrates together such that the cavity in the first substrate is hermetically sealed.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: The present invention determines the resonant frequency of a wireless sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency. The system receives the ring down response of the sensor and determines the resonant frequency of the sensor, which is used to calculate a physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal. The system identifies false locks by detecting an unwanted beat frequency in the coupled signal, as well as determining whether the coupled signal exhibits pulsatile characteristics that correspond to a periodic physiological characteristic, such as blood pressure.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: The present invention determines the resonant frequency of a wireless sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency. The system receives the ring down response of the sensor and determines the resonant frequency of the sensor, which is used to calculate a physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal. The system identifies false locks by detecting an unwanted beat frequency in the coupled signal, as well as determining whether the coupled signal exhibits pulsatile characteristics that correspond to a periodic physiological characteristic, such as blood pressure.

Abstract: A wireless sensor for indicating a physical state within an environment includes a unitary housing defining a cavity. A structure located within the cavity of the housing has elements providing capacitance, the elements being arranged such that the distance and thereby the capacitance of the structure changes when a physical state of the environment changes. The structure has a resonant frequency based at least in part on the capacitance of the structure when in the presence of a fluctuating electromagnetic field. When the sensor is positioned within an environment and is subjected to a fluctuating electromagnetic field, the resonant frequency indicates the physical state of the environment.

Abstract: The progress of a endovascular cardiac repair can be monitored by inserting a pressure transducer sensor using a catheter into a chamber of the heart during endovascular repair and then using a small, hand-held read out device to measure pressure easily, safely, inexpensively and accurately. In one aspect a sensor is introduced into the body by the steps of folding or rolling the sensor into a cylinder, loading it into a catheter, and deploying into the heart chamber by allowing it to unroll or unfold, either by itself or facilitated by the incorporation of a super-elastic alloy component.

Abstract: Aspects of the present invention determine the resonant frequency of a sensor by obtaining sensor signals in response to three energizing signals, measuring the phase of each sensor signal, and using a group phase delay to determine the resonant frequency. The phase difference between the first and second signal is determined as a first group phase delay. The phase difference between the second and third signal is determined as a second group phase delay. The first group phase delay and second group phase delay are compared. Based on the comparison, the system may lock on the resonant frequency of the sensor or adjust a subsequent set of three energizing signals.

Abstract: The present invention determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The system energizes the sensor with a low duty cycle, gated burst of RF energy having a predetermined frequency or set of frequencies and a predetermined amplitude. The energizing signal is coupled to the sensor via magnetic coupling and induces a current in the sensor which oscillates at the resonant frequency of the sensor. The system receives the ring down response of the sensor via magnetic coupling and determines the resonant frequency of the sensor, which is used to calculate the measured physical parameter. The system uses a pair of phase locked loops to adjust the phase and the frequency of the energizing signal.

Abstract: A coupling loop or antenna is provided that can be used with a system that determines the resonant frequency of a sensor by adjusting the phase and frequency of an energizing signal until the frequency of the energizing signal matches the resonant frequency of the sensor. The coupling loop includes multiple loops. Preferably two tuned loops are used for transmitting the energizing signal to the sensor and an un-tuned loop is used for receiving the sensor signal from the sensor. Orientation features on the housing for the coupling loop and the sensor are provided to assist in positioning the coupling loop relative to the sensor to maximize the coupling between the sensor signal and the coupling loop.